Dual-Waveguide Pupil Expander for Holographic Display Viewing Window
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing holographic display devices face challenges in efficiently expanding the viewing window to accommodate head movement while maintaining image quality and minimizing system volume.
Innovation Solution
The use of a dual-waveguide pupil expander configuration, where each waveguide is approximately half the length of a single waveguide, arranged symmetrically to expand the exit pupil in opposite directions, reduces the overall volume occupied by the pupil expander.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single waveguide pupil expander is used to expand the viewing window, then the exit pupil is expanded in one dimension, but the system occupies a large volume and is bulky
Solution Approach 1:
The patent divides a single waveguide pupil expander into two separate waveguide pupil expanders. Each waveguide expands the exit pupil in a different dimension (first waveguide in first dimension, second waveguide in second dimension), achieving two-dimensional viewing window expansion while reducing the volume occupied by each individual waveguide component.
2Manufacturing precision
If the waveguide is oriented at an angle to the viewing plane to form evenly spaced replicas, then uniform pupil expansion is achieved, but the waveguide occupies a larger height in the second dimension
Solution Approach 1:
The patent transitions from using a single waveguide oriented at an angle (occupying height in second dimension) to using two waveguides oriented parallel to the viewing plane. This dimensional reconfiguration achieves the same uniform pupil expansion function while eliminating the height occupation issue, as both waveguides now lie flat in the viewing plane.
3Area of stationary object
If a single long waveguide is used to expand the exit pupil, then the viewing window is expanded, but the system volume and bulkiness increase
Solution Approach 1:
The patent segments a single long waveguide into two shorter waveguides arranged in parallel. Each waveguide has reduced length and occupies less volume individually, while together they achieve the same viewing window expansion as the original single long waveguide, thereby reducing overall system bulkiness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively expands the viewing window in both dimensions, allowing for head movement without compromising image quality, while also reducing the system's bulkiness and volume requirements.
Implementation Method 1
a waveguide pupil expander. The waveguide pupil expander is arranged to expand an exit pupil thereof in a first dimension by a series of internal reflections along the length of the waveguide
Data Source
AI summary
A display device having a viewing window on a viewing plane is described. The display device comprises a picture generating unit, a first waveguide pupil expander and a second waveguide pupil expander. The picture generating unit is arranged to display a picture on a display plane. The picture is a holographic reconstruction formed from a hologram of the picture. The first waveguide pupil expander comprises an input port arranged to receive light of the picture and to expand a first exit pupil thereof in a first dimension. The second waveguide pupil expander comprises an input port arranged to receive light of the picture and to expand a second exit pupil thereof in the first dimension. The first dimension corresponds to a dimension of the viewing window. A method of expanding a viewing window of a display device is also described.